Stack packages having token ring loops

ABSTRACT

Stack packages are provided. The stack package includes a substrate having first and second bond fingers and a plurality of semiconductor chips stacked on the substrate. Each of the plurality of semiconductor chips has an input bonding pad and an output bonding pad. A first interconnection electrically connects the first bond finger to the input bonding pad of a lowermost semiconductor chip of the plurality of semiconductor chips. A second interconnection electrically connects the output bonding pad of a lower semiconductor chip of the plurality of semiconductor chips to the input bonding pad of an upper semiconductor chip stacked on the lower semiconductor chip. A third interconnection electrically connects the output bonding pad of an uppermost semiconductor chip of the plurality of semiconductor chips to the second bond finger.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C 119(a) to KoreanApplication No. 10-2012-0150085, filed on Dec. 20, 2012, in the Koreanintellectual property Office, which is incorporated herein by referencein its entirety as set forth in full.

BACKGROUND

Embodiments of the present disclosure relate to semiconductor stackpackages and, more particularly, to stack packages having token ringloops.

In the electronics industry, high reliable electronic devices fabricatedat a low cost are increasingly in demand with the development oflighter, smaller, faster, multi-functional, and higher performanceelectronic systems. In response to such a demand, packaging techniqueshave been continuously improved or developed. The packaging techniquesare used to protect semiconductor chips manufactured using a siliconwafer from an external environment and to electrically connect thesemiconductor chips to other semiconductor chips or package substrates.Recently, stack packages have been widely used in the electronicsindustry. The stack packages may be fabricated by vertically stacking aplurality of semiconductor chips on a package substrate.

In the stack packages, the stacked chips may be electrically connectedto the package substrate through bonding wires. The bonding wires may bebonded to bonding pads of the semiconductor chips. Thus, thesemiconductor chips of the stack package should be vertically stacked toexpose the bonding pads. That is, the semiconductor chips may be stackedto have a step structure. In such a case, a series of wire bondingprocesses may be performed between bond fingers of the substrate and thebonding pads of the stacked semiconductor chips to electrically connectthe stacked semiconductor chips to the substrate. However, in such acase, electrical signals are simultaneously transmitted through thebonding wires, and all the stacked semiconductor chips may suffer frommaximum currents. Accordingly, the power consumption of the stackpackage may be increased.

SUMMARY

Various embodiments are directed to stack packages having token ringloops.

According to some embodiments, a stack package includes a substratehaving first and second bond fingers and a plurality of semiconductorchips stacked on the substrate. Each of the plurality of semiconductorchips has an input bonding pad and an output bonding pad. A firstinterconnection electrically connects the first bond finger to the inputbonding pad of a lowermost semiconductor chip of the plurality ofsemiconductor chips. A second interconnection electrically connects theoutput bonding pad of a lower semiconductor chip of the plurality ofsemiconductor chips to the input bonding pad of an upper semiconductorchip stacked on the lower semiconductor chip. A third interconnectionelectrically connects the output bonding pad of an uppermostsemiconductor chip of the plurality of semiconductor chips to the secondbond finger.

According to further embodiments, a stack package includes a substratehaving first and second bond fingers and a plurality of semiconductorchips stacked on the substrate. Each of the plurality of semiconductorchips has an input bonding pad, an output bonding pad, and a dummy pad.A first interconnection electrically connects the first bond finger tothe input bonding pad of a lowermost semiconductor chip of the pluralityof semiconductor chips. A second interconnection electrically connectsthe output bonding pad of a lower semiconductor chip of the plurality ofsemiconductor chips to the input bonding pad of an upper semiconductorchip stacked on the lower semiconductor chip. A third interconnectionelectrically connects the output bonding pad of an upper semiconductorchip of the plurality of semiconductor chips to the dummy pad of a lowersemiconductor chip under the upper semiconductor chip. A fourthinterconnection electrically connects the dummy pad of a lowermostsemiconductor chip of the plurality of semiconductor chips to the secondbond finger.

According to further embodiments, a stack package includes a substrateand a first semiconductor chip group having a plurality of firstsemiconductor chips stacked on the substrate. The substrate has a firstbond finger, a second bond finger, and a third bond finger. Each of thefirst semiconductor chips has an input bonding pad, an output bondingpad, and a dummy pad. A second semiconductor chip group including aplurality second semiconductor chips is stacked on the firstsemiconductor chip group. Each of the second semiconductor chips has aninput bonding pad, an output bonding pad, and a dummy pad. A first tokenring loop includes a first interconnection, a second interconnection, athird interconnection, and a fourth interconnection. The firstinterconnection of the first token ring loop electrically connects thefirst bond finger of the substrate to the input bonding pad of alowermost first semiconductor chip of the first semiconductor chips. Thesecond interconnection of the first token ring loop electricallyconnects the output bonding pad of a lower first semiconductor chip ofthe first semiconductor chips to the input bonding pad of an upper firstsemiconductor chip stacked on the lower first semiconductor chip. Thethird interconnection of the first token ring loop electrically connectsthe output bonding pad of an upper first semiconductor chip of the firstsemiconductor chips to the dummy pad of a lower first semiconductor chipunder the upper first semiconductor chip. The fourth interconnection ofthe first token ring loop electrically connects the dummy pad of alowermost first semiconductor chip of the first semiconductor chips tothe second bond finger of the substrate. A second token ring loopincludes a first interconnection, a second interconnection, a thirdinterconnection, and a fourth interconnection. The first interconnectionof the second token ring loop electrically connects the second bondfinger of the substrate to the input bonding pad of a lowermost secondsemiconductor chip of the second semiconductor chips. The secondinterconnection of the second token ring loop electrically connects theoutput bonding pad of a lower second semiconductor chip of the secondsemiconductor chips to the input bonding pad of an upper secondsemiconductor chip stacked on the lower second semiconductor chip. Thethird interconnection of the second token ring loop electricallyconnects the output bonding pad of an upper second semiconductor chip ofthe second semiconductor chips to the dummy pad of a lower secondsemiconductor chip under the upper second semiconductor chip. The fourthinterconnection of the second token ring loop electrically connects thedummy pad of a lowermost second semiconductor chip of the secondsemiconductor chips to the third bond finger of the substrate.

According to further embodiments, a stack package includes a substratehaving a first bond finger group and a second bond finger group. Each ofthe first and second bond finger groups includes a first bond finger, asecond bond finger, and a third bond finger. First semiconductor chipgroups and second semiconductor chip groups are alternately andrepeatedly stacked on the substrate. Each of the first semiconductorchip groups includes first semiconductor chips which are stacked, andeach of the second semiconductor chip groups includes secondsemiconductor chips which are stacked. Each of the first and secondsemiconductor chips has an input bonding pad, an output bonding pad, anda dummy pad. A first group of first token ring loop includes: a firstinterconnection to electrically connect the first bond finger of thefirst bond finger group to the input bonding pad of a lowermost firstsemiconductor chip in a lower group of the first semiconductor chipgroups; a second interconnection to electrically connect the outputbonding pad of the lowermost first semiconductor chip in the lower groupof the first semiconductor chip groups to the input bonding pad of anupper first semiconductor chip on the lowermost first semiconductorchip; a third interconnection to electrically connect the output bondingpad of the upper first semiconductor chip to the dummy pad of a lowerfirst semiconductor chip under the upper first semiconductor chip; and afourth interconnection to electrically connect the dummy pad of thelowermost first semiconductor chip to the second bond finger of thefirst bond finger group. A first group of second token ring loopincludes: a first interconnection to electrically connect the secondbond finger of the first bond finger group to the input bonding pad of alowermost first semiconductor chip in an upper group of the firstsemiconductor chip groups; a second interconnection to electricallyconnect the output bonding pad of the lowermost first semiconductor chipin the upper group of the first semiconductor chip groups to the inputbonding pad of an upper first semiconductor chip on the lowermost firstsemiconductor chip; a third interconnection to electrically connect theoutput bonding pad of the upper first semiconductor chip to the dummypad of a lower first semiconductor chip under the upper firstsemiconductor chip; and a fourth interconnection to electrically connectthe dummy pad of the lowermost first semiconductor chip to the thirdbond finger of the first bond finger group. A second group of firsttoken ring loop includes: a first interconnection to electricallyconnect the first bond finger of the second bond finger group to theinput bonding pad of a lowermost second semiconductor chip in a lowergroup of the second semiconductor chip groups; a second interconnectionto electrically connect the output bonding pad of the lowermost secondsemiconductor chip in the lower group of the second semiconductor chipgroups to the input bonding pad of an upper second semiconductor chip onthe lowermost second semiconductor chip; a third interconnection toelectrically connect the output bonding pad of the upper secondsemiconductor chip to the dummy pad of a lower second semiconductor chipunder the upper second semiconductor chip; and a fourth interconnectionto electrically connect the dummy pad of the lowermost secondsemiconductor chip to the second bond finger of the second bond fingergroup. A second group of second token ring loop includes a firstinterconnection for electrically connecting the second bond finger ofthe second bond finger group to the input bonding pad of a lowermostsecond semiconductor chip in an upper group of the second semiconductorchip groups, a second interconnection for electrically connecting theoutput bonding pad of the lowermost second semiconductor chip in theupper group of the second semiconductor chip groups to the input bondingpad of an upper second semiconductor chip on the lowermost secondsemiconductor chip, a third interconnection for electrically connectingthe output bonding pad of the upper second semiconductor chip to thedummy pad of a lower second semiconductor chip under the upper secondsemiconductor chip, and a fourth interconnection for electricallyconnecting the dummy pad of the lowermost second semiconductor chip tothe third bond finger of the second bond finger group.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the inventive concept will become more apparent in viewof the attached drawings and accompanying detailed description, inwhich:

FIG. 1 is a cross sectional view illustrating a stack package accordingto an embodiments;

FIG. 2 is a plan view illustrating a token ring connection structure ofthe stack package shown in FIG. 1;

FIG. 3 is a cross sectional view illustrating a stack package accordingto another embodiments;

FIGS. 4A and 4B are plan views illustrating token ring connectionstructures of the stack package shown in FIG. 3;

FIG. 5 is a cross sectional view illustrating a stack package accordingto still another embodiments; and

FIGS. 6A, 6B, 6C, 7A, 7B and 7C are plan views illustrating token ringconnection structures of the stack package shown in FIG. 5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a cross sectional view illustrating a stack package accordingto an embodiments, and FIG. 2 is a plan view illustrating a token ringconnection structure of the stack package shown in FIG. 1. FIG. 1 is across sectional view taken along a line I-I′ of FIG. 2, and wireinterconnections of FIG. 2 are not illustrated in FIG. 1 for the purposeof ease and convenience in explanation. Referring to FIGS. 1 and 2, astack package 100 may be configured to include a substrate 110 and aplurality of semiconductor chips 210, 220, 230, 240, 250, and 260sequentially stacked on the substrate 110. An insulating adhesive 120may be disposed between the substrate 110 and the semiconductor chips210, 220, 230, 240, 250, and 260. The substrate 110 may include a firstbond finger 111 and a second bond finger 112. In some embodiments, thefirst bond finger 111 may be a terminal receiving signals outputted froman external device, and the second bond finger 112 may be a terminaloutputting signals generated in the stack package 100 to the externaldevice. That is, the first bond finger 111 may act as an input terminalof the stack package 100, and the second bond finger 112 may act as anoutput terminal of the stack package 100. Accordingly, the first andsecond bond fingers 111 and 112 may be electrically connected to anexternal device, for example, an external controller chip. The first andsecond bond fingers 111 and 112 may be disposed on a surface of thesubstrate 110 to be spaced apart from each other.

The plurality of semiconductor chips 210, 220, 230, 240, 250, and 260may have the same structure. However, in some embodiments, the pluralityof semiconductor chips 210, 220, 230, 240, 250, and 260 may havedifferent structures and functions from each other. In any case, each ofthe semiconductor chips 210, 220, 230, 240, 250, and 260 may have aninput bonding pad and an output bonding pad. For example, thesemiconductor chip 210 may have an input bonding pad 211 and an outputbonding pad 212. The semiconductor chip 220 may have an input bondingpad 221 and an output bonding pad 222. The semiconductor chip 230 mayhave an input bonding pad 231 and an output bonding pad 232. Thesemiconductor chip 240 may have an input bonding pad 241 and an outputbonding pad 242. The semiconductor chip 250 may have an input bondingpad 251 and an output bonding pad 252, and the semiconductor chip 260may have an input bonding pad 261 and an output bonding pad 262. Theinput bonding pads 211, 221, 231, 241, 251, and 261 and the outputbonding pads 212, 222, 232, 242, 252, and 262 may be disposed on topsurfaces of the semiconductor chips 210, 220, 230, 240, 250, and 260 andmay be spaced apart from each other.

The semiconductor chips 210, 220, 230, 240, 250, and 260 may be stackedon the substrate 110 to have a step structure. This step structure maybe to expose the first and second bond fingers 111 and 112, the inputbonding pads 211, 221, 231, 241, 251, and 261, and the output bondingpads 212, 222, 232, 242, 252, and 262. The input/output bonding pad 261and 262 of semiconductor chip 260 may be electrically connected to eachother through an internal circuit 263 integrated in the semiconductorchip 260. For example, the input bonding pad 261 and the output bondingpad 262 of the semiconductor chip 260 may be electrically connected toan input terminal and an output terminal of the internal circuit 263formed in the semiconductor chip 260, respectively. Each of thesemiconductor chips 220, 230, 240, 250, and 260 may also have the sameor similar configuration as the semiconductor chip 260. In someembodiments, each of the internal circuits may correspond to a signaldelay circuit.

A token ring connection structure may be disposed between the first bondfinger 111 of the substrate 110, the input bonding pads 211, 221, 231,241, 251, and 261 and the output bonding pads 212, 222, 232, 242, 252,and 262 of the semiconductor chips 210, 220, 230, 240, 250, and 260, andthe second bond finger 112 of the substrate 110. The token ringconnection structure may include metal wires 291, 292, 293, 294, 295,296, and 297. Specifically, the first bond finger 111 of the substrate110 may be electrically connected to the input bonding pad 211 of thesemiconductor chip 210 corresponding to a lowermost semiconductor chipamong the semiconductor chips 210, 220, 230, 240, 250 and 260 through afirst interconnection, for example, a first metal wire 291.

The output bonding pad 212 of the semiconductor chip 210 may beelectrically connected to the input bonding pad 221 of the semiconductorchip 220 stacked on the semiconductor chip 210 through a secondinterconnection, for example, a second metal wire 292. Thisinterconnection scheme to connect the output bonding pad of a lowersemiconductor chip to the input bonding pad of an upper semiconductorchip through the second metal wire may be repeatedly applied to all ofthe semiconductor chips between the lowermost semiconductor chip 210 andthe uppermost semiconductor chip 260. That is, the output bonding pad222 of the semiconductor chip 220 may be electrically connected to theinput bonding pad 231 of the semiconductor chip 230 stacked on thesemiconductor chip 220 through a second metal wire 293. The outputbonding pad 232 of the semiconductor chip 230 may be electricallyconnected to the input bonding pad 241 of the semiconductor chip 240stacked on the semiconductor chip 230 through a second metal wire 294.The output bonding pad 242 of the semiconductor chip 240 may beelectrically connected to the input bonding pad 251 of the semiconductorchip 250 stacked on the semiconductor chip 240 through a second metalwire 295. The output bonding pad 252 of the semiconductor chip 250 maybe electrically connected to the input bonding pad 261 of thesemiconductor chip 260 stacked on the semiconductor chip 250 through asecond metal wire 296.

Further, the output bonding pad 262 of the semiconductor chip 260 may beelectrically connected to the second bond finger 112 of the substrate110 through a third interconnection, for example, a third metal wire297. As a result, the first bond finger 111 (e.g., an input bond finger)may be connected to the second bond finger 112 (e.g., an output bondfinger) through a signal transmission path having a token ringconnection structure (or a token ring loop) that includes: the firstmetal wire 291, the input bonding pad 211 and the output bonding pad 212of the semiconductor chip 210, the second metal wire 292, the inputbonding pad 221 and the output bonding pad 222 of the semiconductor chip220, the second metal wire 293, the input bonding pad 231 and the outputbonding pad 232 of the semiconductor chip 230, the second metal wire294, the input bonding pad 241 and the output bonding pad 242 of thesemiconductor chip 240, the second metal wire 295, the input bonding pad251 and the output bonding pad 252 of the semiconductor chip 250, thesecond metal wire 296, the input bonding pad 261 and the output bondingpad 262 of the semiconductor chip 260, and the third metal wire 297.That is, the semiconductor chips 210, 220, 230, 240, 250, and 260 may beserially connected to each other through the token ring connectionstructure. Thus, if the delay time of the internal circuit of eachsemiconductor chip 210, 220, 230, 240, 250. or 260 is appropriatelycontrolled, the current flowing through the semiconductor chips 210,220, 230, 240, 250, and 260 may be reduced to prevent the stack package100 from suffering due to a maximum current. That is, the token ringstructure may reduce the power consumption of the stack package 100.

FIG. 3 is a cross sectional view illustrating a stack package accordingto another embodiments, and FIGS. 4A and 4B are plan views illustratingtoken ring connection structures of the stack package shown in FIG. 3.Further, FIG. 3 is a cross sectional view taken along a line III-III′ ofFIGS. 4A and 4B. For the purpose of ease and convenience in explanation,wire interconnections of FIGS. 4A and 4B are not illustrated in FIG. 3.Referring to FIGS. 3, 4A, and 4B, a stack package 300 according to thepresent embodiment may be configured to include a first semiconductorchip group 320 and a second semiconductor chip group 330 which aresequentially stacked on a substrate 300. An interposer 340 may bedisposed between the first and second semiconductor chip groups 320 and330. However, in some embodiments, the second semiconductor chip group330 may be directly stacked on the first semiconductor chip group 320without use of the interposer 340. The substrate 300 may have a firstbond finger 311, a second bond finger 312, and a third bond finger 313which are disposed to be adjacent to each other on a surface of a bodyof the substrate 300. In some embodiments, the first bond finger 311 maybe a terminal receiving signals outputted from an external device, andthe third bond finger 313 may be a terminal outputting signals generatedin the stack package 300 to the external device. That is, the first bondfinger 311 may act as an input terminal of the stack package 300, andthe third bond finger 313 may act as an output terminal of the stackpackage 300. Accordingly, the first and third bond fingers 311 and 313may be electrically connected to an external device, for example, anexternal controller chip. The second bond finger 312 disposed betweenthe first and third bond fingers 311 and 313 may act as a signaltransmission terminal between the first semiconductor chip group 320 andthe second semiconductor chip group 330. Thus, in some embodiments, thenumber of the second bond finger 312 may be two or more. That is, thenumber of the second bond finger 312 may be determined according to thenumber of the semiconductor chip groups.

The first semiconductor chip group 320 may include first semiconductorchips 321 and 322 which are sequentially stacked on the substrate 310with an adhesive 350 interposed therebetween. Although the presentembodiment is described in conjunction with an example that the numberof first semiconductor chips 321 and 322 is two, the inventive conceptis not limited thereto. For example, the first semiconductor chip group320 may include three or more first semiconductor chips. Each of thefirst semiconductor chips 321 and 322 may have an input bonding pad 411or 421, an output bonding pad 412 or 422, and a dummy pad 413 or 423which are disposed to be spaced apart from each other on a surfacethereof. The first semiconductor chips 321 and 322 may be stacked tohave a step structure. Thus, the input bonding pads 411 and 421, theoutput bonding pads 412 and 422, and the dummy pads 413 and 423, whichare disposed on edges of the first semiconductor chips 321 and 322, maybe exposed.

The second semiconductor chip group 330 may be disposed on theinterposer 340. However, in the event that the interposer 340 is absent,the second semiconductor chip group 330 is directly disposed on asurface of the first semiconductor chip group 320 opposite to thesubstrate 300. The second semiconductor chip group 330 may includesecond semiconductor chips 331 and 332 which are sequentially stackedwith the adhesive 350 interposed therebetween. Although the presentembodiment is described in conjunction with an example that the numberof second semiconductor chips 331 and 332 is two, the inventive conceptis not limited thereto. For example, the second semiconductor chip group330 may include three or more second semiconductor chips. Each of thesecond semiconductor chips 331 and 332 may have an input bonding pad 431or 441, an output bonding pad 432 or 442, and a dummy pad 433 or 443which are disposed to be spaced apart from each other on a surfacethereof. The second semiconductor chips 331 and 332 may have the samefunction and configuration as the first semiconductor chips 321 and 322.Further, the second semiconductor chips 331 and 332 may be stacked tohave the same structure (e.g., a step structure) as the firstsemiconductor chips 321 and 322. Thus, the input bonding pads 431 and441, the output bonding pads 432 and 442, and the dummy pads 433 and443, which are disposed on edges of the second semiconductor chips 331and 332, may be exposed.

Although the first and second semiconductor chip groups 320 and 330 aredistinguished form each other in the present embodiment, the embodimentsare not limited thereto. For example, the first semiconductor chip group320 may be the same semiconductor chip group as the second semiconductorchip group 330, and the first and second semiconductor chip groups 320and 330 may be merely distinguished form each other according tovertical stack positions thereof. Thus, the first semiconductor chips321 and 322 constituting the first semiconductor chip group 320 may besubstantially the same configuration as the second semiconductor chips331 and 332 constituting the second semiconductor chip group 330.

According to the present embodiment, the second semiconductor chip group330 may be vertically aligned with the first semiconductor chip group320. That is, the lowermost first semiconductor chip 321 of the firstsemiconductor chip group 320 and the lowermost second semiconductor chip331 of the second semiconductor chip group 330 may be vertically alignedwith each other. A sidewall of the lowermost first semiconductor chip321 and a sidewall of the lowermost second semiconductor chip 331 may belocated on a single vertical line. Similarly, the uppermost firstsemiconductor chip 322 of the first semiconductor chip group 320 and theuppermost second semiconductor chip 332 of the second semiconductor chipgroup 330 may be vertically aligned with each other. A sidewall of theuppermost first semiconductor chip 322 and a sidewall of the uppermostsecond semiconductor chip 332 may be located on a single vertical line.Thus, the stack package 300 may employ other token ring connectionstructures having different configuration from the token ring connectionstructure of the previous embodiment illustrated in FIGS. 1 and 2.

Specifically, as illustrated in FIG. 4A, the input bonding pad 411 ofthe first semiconductor chip 321 corresponding to a lowermostsemiconductor chip of the first semiconductor chip group 320 may beelectrically connected to the first bond finger 311 of the substrate 310through a first interconnection, for example, a first metal wire 391.The output bonding pad 412 of the lowermost first semiconductor chip 321may be electrically connected to the input bonding pad 421 of the firstsemiconductor chip 322 disposed on the first semiconductor chip 321through a second interconnection, for example, a second metal wire 392.If the first semiconductor chip group 320 includes three or more firstsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 412 of the first semiconductorchip 321 to the input bonding pad 421 of the first semiconductor chip322 through the second metal wire 392 may be repeatedly applied to allthe first semiconductor chips between the lowermost first semiconductorchip and the uppermost first semiconductor chip. The output bonding pad422 of the first semiconductor chip 322 corresponding to an uppermostsemiconductor chip of the first semiconductor chip group 320 may beelectrically connected to the dummy pad 413 of the first semiconductorchip 321 under the first semiconductor chip 322 through a thirdinterconnection, for example, a third metal wire 393. If the firstsemiconductor chip group 320 includes three or more first semiconductorchips which are sequentially stacked, the interconnection scheme toconnect the output bonding pad 422 of the first semiconductor chip 322to the dummy pad 413 of the first semiconductor chip 321 through thethird metal wire 393 may be repeatedly applied to all the firstsemiconductor chips between the lowermost first semiconductor chip andthe uppermost first semiconductor chip. The dummy pad 413 of thelowermost first semiconductor chip 321 may be electrically connected tothe second bond finger 312 of the substrate 310 through a fourthinterconnection, for example, a fourth metal wire 394.

In some embodiments, if the first semiconductor chip group 320 includesthree or more first semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost first semiconductor chip may beelectrically connected to a dummy pad of one of the first semiconductorchips under the uppermost first semiconductor chip through the thirdmetal wire 393. The dummy pad may be electrically connected to thesecond bond finger 312 of the substrate 310 through the fourth metalwire 394. Alternatively, if the first semiconductor chip group 320includes three or more first semiconductor chips which are sequentiallystacked, the output bonding pad of the uppermost first semiconductorchip may be electrically connected to a dummy pad of one of the firstsemiconductor chips under the uppermost first semiconductor chip throughthe third metal wire 393. The dummy pad may be electrically connected tothe second bond finger 312 of the substrate 310 via a dummy pad ofanother first semiconductor chip.

As described above, the first bond finger 311 of the substrate 310 maybe connected to the second bond finger 312 through a first token ringloop including the first metal wire 391 the input bonding pad 411 andthe output bonding pad 412 of the first semiconductor chip 321. Thefirst token ring loop may also include the second metal wire 392, theinput bonding pad 421 and the output bonding pad 422 of the firstsemiconductor chip 322. In addition, the first token ring loop may alsoinclude the third metal wire 393, the dummy pad 413 of the firstsemiconductor chip 321, and the fourth metal wire 394.

Subsequently, as illustrated in FIG. 4B, the input bonding pad 431 ofthe second semiconductor chip 331 corresponding to a lowermostsemiconductor chip of the second semiconductor chip group 330 may beelectrically connected to the second bond finger 312 of the substrate310 through a first interconnection, for example, a first metal wire395. The second bond finger 312 may correspond to a bond finger which isconnected to the dummy pad 413 of the lowermost first semiconductor chip321 of the first semiconductor chip group 320. The output bonding pad432 of the second semiconductor chip 331 may be electrically connectedto the input bonding pad 441 of the second semiconductor chip 332disposed on the second semiconductor chip 331 through a secondinterconnection, for example, a second metal wire 396. If the secondsemiconductor chip group 330 includes three or more second semiconductorchips which are sequentially stacked, the interconnection scheme forconnecting the output bonding pad 432 of the lower second semiconductorchip 331 to the input bonding pad 441 of the upper second semiconductorchip 332 through the second metal wire 396 may be repeatedly applied.The interconnection scheme may be applied to all the secondsemiconductor chips between the lowermost second semiconductor chip andthe uppermost second semiconductor chip. The output bonding pad 442 ofthe second semiconductor chip 332 corresponding to an uppermostsemiconductor chip of the second semiconductor chip group 330 may beelectrically connected to the dummy pad 433 of the second semiconductorchip 331 under the second semiconductor chip 332 through a thirdinterconnection, for example, a third metal wire 397.

If the second semiconductor chip group 330 includes three or more secondsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 442 of the upper secondsemiconductor chip 332 to the dummy pad 433 of the lower secondsemiconductor chip 331 through the third metal wire 397 may berepeatedly applied. The interconnection scheme may be applied to all ofthe second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Thedummy pad 433 of the lowermost second semiconductor chip 331 may beelectrically connected to the third bond finger 313 of the substrate 310through a fourth interconnection, for example, a fourth metal wire 398.

In some embodiments, if the second semiconductor chip group 330 includesthree or more second semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost second semiconductor chip may beelectrically connected to a dummy pad. The dummy pad may be of one ofthe second semiconductor chips under the uppermost second semiconductorchip through the third metal wire 397. The dummy pad may then beelectrically connected to the third bond finger 313 of the substrate 310through the fourth metal wire 398. Alternatively, if the secondsemiconductor chip group 330 includes three or more second semiconductorchips which are sequentially stacked, the output bonding pad of theuppermost second semiconductor chip may be electrically connected. Theconnection may be to a dummy pad of one of the second semiconductorchips under the uppermost first semiconductor chip through the thirdmetal wire 397 The dummy pad may then be electrically connected to thethird bond finger 313 of the substrate 310 via a dummy pad of anothersecond semiconductor chip.

As described above, the second bond finger 312 of the substrate 310 maybe connected to the third bond finger 313 through a second token ringloop including the first metal wire 395, the input bonding pad 431 andthe output bonding pad 432 of the second semiconductor chip 331. Thesecond token ring loop may include the second metal wire 396, the inputbonding pad 441 and the output bonding pad 442 of the secondsemiconductor chip 332. The second token ring loop may also include thethird metal wire 397, the dummy pad 433 of the second semiconductor chip331, and the fourth metal wire 398. The second token ring loop and thefirst token ring loop may constitute a total token ring loop of thestack package 300.

FIG. 5 is a cross sectional view illustrating a stack package accordingto still another embodiments, and FIGS. 6A<6B, 6C, 7A, 7B and 7C areplan views illustrating token ring connection structures of the stackpackage shown in FIG. 5. FIG. 5 is a cross sectional view taken along aline V-V′ of FIGS. 6A, 6B, 6C, 7A, 7B and 7C, and wire interconnectionsof FIGS. 6A, 6B, 6C, 7A, 7B and 7C are not illustrated in FIG. 5 for thepurpose of ease and convenience in explanation.

Referring to FIG. 5, a package 500 according to the present embodimentmay include first semiconductor chip groups 600, 600′ and 600″ andsecond semiconductor chip groups 700, 700′ and 700″ which arealternately and repeatedly stacked on a substrate 510. Although thepresent embodiment is described in conjunction with an example that twosemiconductor chip groups are alternately and repeatedly stacked, theinventive concept is not limited thereto. That is, the presentembodiment is equally applicable to any stack packages including threeor more semiconductor chip groups which are alternately and repeatedlystacked. Further, although the present embodiment is described inconjunction with an example that each semiconductor chip group includethree semiconductor chips, the inventive concept is not limited thereto.That is, the present embodiment is equally applicable to any stackpackages that each semiconductor chip group includes four or moresemiconductor chips.

The first semiconductor chip group 600 disposed at a lowermost level ofthe three first semiconductor chip groups 600, 600′ and 600″ may includea pair of first semiconductor chips 610 and 620 which are stacked in afirst direction to have a step structure. The first semiconductor chipgroup 600′ disposed at a middle level of the three first semiconductorchip groups 600, 600′ and 600″ may include a pair of first semiconductorchips 610′ and 620′ which are stacked in the first direction to have astep structure. The first semiconductor chip group 600″ disposed at anuppermost level of the three first semiconductor chip groups 600, 600′and 600″ may include a pair of first semiconductor chips 610″ and 620″which are stacked in the first direction to have a step structure. Thesecond semiconductor chip group 700 disposed at a lowermost level of thethree second semiconductor chip groups 700, 700′ and 700″ may include apair of second semiconductor chips 710 and 720 which are stacked in asecond direction opposite to the first direction to have a stepstructure. The second semiconductor chip group 700′ may be disposed at amiddle level of the three second semiconductor chip groups 700, 700′ and700″ that may include a pair of second semiconductor chips 710′ and 720′which are stacked in the second direction to have a step structure. Thesecond semiconductor chip group 700″ disposed at an uppermost level ofthe three second semiconductor chip groups 700, 700′ and 700″ that mayinclude a pair of second semiconductor chips 710″ and 720″ which arestacked in the first direction to have a step structure. As describedabove, the first direction may be a direction which is opposite to thesecond direction. However, in some embodiments, the first direction maybe a different direction from the second direction, but not opposite tothe second direction. Further, in some embodiments, the number of thesemiconductor chips constituting each semiconductor chip group may bethree or more. An adhesive 530 may be disposed between the substrate 510and the lowermost semiconductor chip 610 as well as between the firstand second semiconductor chips constituting the first and secondsemiconductor chip groups.

As illustrated in FIGS. 6A, 6B and 6C, a first bond finger groupincluding first to fourth bond fingers 531, 532, 533 and 534 may bedisposed on an edge of a first surface of the substrate 510 and may bespaced apart from each other. In addition, as illustrated in FIGS. 7A,7B and 7C, a second bond finger group including first to fourth bondfingers 541, 542, 543 and 544 may be disposed on another edge of thefirst surface of the substrate 510 and may be spaced apart from eachother. In some embodiments, the first bond finger 531 of the first bondfinger group and the first bond finger 541 of the second bond fingergroup may act as input terminals receiving signals outputted from anexternal device. The third bond finger 533 of the first bond fingergroup and the third bond finger 543 of the second bond finger group mayact as output terminals outputting signals generated in the stackpackage 500 to the external device. Accordingly, the first and thirdbond fingers 531 and 533 of the first bond finger group may beelectrically connected to an external device. The external device may befor example, an external controller chip, and the first and third bondfingers 541 and 543 of the second bond finger group may also beelectrically connected to the external controller chip. The second bondfinger 532 disposed between the first and third bond fingers 531 and 533of the first bond finger group may act as a signal transmission terminalbetween the first semiconductor chip groups 600 and 600′. Further, thethird bond finger 533 disposed between the second and fourth bondfingers 532 and 534 of the first bond finger group may act as a signaltransmission terminal between the first semiconductor chip groups 600′and 600″. Thus, the number of the bond fingers between the first andfourth bond fingers 531 and 534 of the first bond finger group may betwo or more. That is, the number of the bond fingers between the firstand fourth bond fingers 531 and 534 of the first bond finger group maybe determined according to the number of the first semiconductor chipgroups 600, 600′, and 600″. Similarly, the second bond finger 542disposed between the first and third bond fingers 541 and 543 of thesecond bond finger group may act as a signal transmission terminalbetween the second semiconductor chip groups 700 and 700′. Further, thethird bond finger 543 disposed between the second and fourth bondfingers 542 and 544 of the second bond finger group may act as a signaltransmission terminal between the second semiconductor chip groups 700′and 700″. Thus, the number of the bond fingers between the first andfourth bond fingers 541 and 544 of the second bond finger group may betwo or more. That is, the number of the bond fingers between the firstand fourth bond fingers 541 and 544 of the second bond finger group maybe determined according to the number of the second semiconductor chipgroups 700, 700′ and 700″.

Each of the first semiconductor chips 610, 620, 610′, 620′, 610″ and620″ constituting the first semiconductor chip groups 600, 600′ and 600″may include an input bonding pad, an output bonding pad and a dummy pad.For example, the first semiconductor chips 610, 620, 610′, 620′, 610″and 620″ may include input bonding pads 611, 621, 611′, 621′, 611″ and621″, respectively. Further, the first semiconductor chips 610, 620,610′, 620′, 610″ and 620″ may include output bonding pads 612, 622,612′, 622′, 612″ and 622″, respectively. Moreover, the firstsemiconductor chips 610, 620, 610′, 620′, 610″ and 620″ may includedummy pads 613, 623, 613′, 623′, 613″ and 623″, respectively. The inputbonding pads 611, 621, 611′, 621′, 611″ and 621″, the output bondingpads 612, 622, 612′, 622′, 612″ and 622″, and the dummy pads 613, 623,613′, 623′, 613″ and 623″ may be exposed because the first semiconductorchips of each of the first semiconductor chip groups 600, 600′ and 600″are stacked to have a step structure.

Similarly, each of the second semiconductor chips 710, 720, 710′, 720′,710″ and 720″ constituting the second semiconductor chip groups 700,700′ and 700″ may also include an input bonding pad, an output bondingpad, and a dummy pad. For example, the second semiconductor chips 710,720, 710′, 720′, 710″ and 720″ may include input bonding pads 711, 721,711′, 721′, 711″ and 721″, respectively. Further, the secondsemiconductor chips 710, 720, 710′, 720′, 710″ and 720″ may includeoutput bonding pads 712, 722, 712′, 722′, 712″ and 722″, respectively.Moreover, the second semiconductor chips 710, 720, 710′, 720′, 710″ and720″ may include dummy pads 713, 723, 713′, 723′, 713″ and 723″,respectively. The input bonding pads 711, 721, 711′, 721′, 711″ and721″, the output bonding pads 712, 722, 712′, 722′, 712″ and 722″, andthe dummy pads 713, 723, 713′, 723′, 713″ and 723″ may be exposedbecause the second semiconductor chips of each of the secondsemiconductor chip groups 700, 700′ and 700″ are stacked to have a stepstructure.

In the stack package 500, the first semiconductor chips 610, 620, 610′,620′, 610″ and 620″ of the first semiconductor chip groups 600, 600′ and600″ may be electrically connected to the first, second, third andfourth bond fingers 531, 532, 533 and 534 of the first bond finger groupthrough a token ring connection structure.

Specifically, as illustrated in FIG. 6A, the input bonding pad 611 ofthe lower first semiconductor chip 610 of the first semiconductor chipgroup 600 disposed at a lowermost level of the three first semiconductorchip groups 600, 600′ and 600″ may be electrically connected. Theconnection may be to the first bond finger 531 of the substrate 510through a first interconnection, for example, a first metal wire 801.The output bonding pad 612 of the lower first semiconductor chip 610 maybe electrically connected to the input bonding pad 621 of the upperfirst semiconductor chip 620. The upper first semiconductor chip 620 maybe disposed on the lower first semiconductor chip 610 through a secondinterconnection, for example, a second metal wire 802. If the firstsemiconductor chip group 600 includes three or more first semiconductorchips which are sequentially stacked, the interconnection scheme toconnect the output bonding pad 612 of the lower first semiconductor chip610 to the input bonding pad 621 of the upper first semiconductor chip620 through the second metal wire 802 may be repeatedly applied. Theinterconnection scheme may be applied to all of the first semiconductorchips between the lowermost first semiconductor chip and the uppermostfirst semiconductor chip. The output bonding pad 622 of the firstsemiconductor chip 620 corresponding to an uppermost semiconductor chipof the first semiconductor chip group 600 may be electrically connectedto the dummy pad 613 of the first semiconductor chip 610 under the firstsemiconductor chip 620 through a third interconnection, for example, athird metal wire 803. If the first semiconductor chip group 600 includesthree or more first semiconductor chips which are sequentially stacked,the interconnection scheme to connect the output bonding pad 622 of thefirst semiconductor chip 620 to the dummy pad 613 of the firstsemiconductor chip 610 through the third metal wire 803 may berepeatedly applied. The interconnection scheme may be applied to all ofthe first semiconductor chips between the lowermost first semiconductorchip and the uppermost first semiconductor chip. The dummy pad 613 ofthe lowermost first semiconductor chip 610 may be electrically connectedto the second bond finger 532 of the substrate 510 through a fourthinterconnection. The fourth interconnection may be for example, a fourthmetal wire 804.

In some embodiments, if the first semiconductor chip group 600 includesthree or more first semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost first semiconductor chip may beelectrically connected to a dummy pad chip through the third metal wire803. The dummy pad may be of one of the first semiconductor chips underthe uppermost first semiconductor. The dummy pad may also beelectrically connected to the second bond finger 532 of the substrate510 through the fourth metal wire 804. Alternatively, if the firstsemiconductor chip group 600 includes three or more first semiconductorchips which are sequentially stacked, the output bonding pad of theuppermost first semiconductor chip may be electrically connected. Theconnection may be to a dummy pad of one of the first semiconductor chipsunder the uppermost first semiconductor chip through the third metalwire 803. The dummy pad may be electrically connected to the second bondfinger 532 of the substrate 510 via a dummy pad of another firstsemiconductor chip.

As described above, the first bond finger 531 of the substrate 510 maybe connected to the second bond finger 532 through a first token ringloop which includes the first metal wire 801. The first bond finger 531may also be connected to the input bonding pad 611 and the outputbonding pad 612 of the first semiconductor chip 610. In addition, thefirst bond finger 531 may be connected to the second metal wire 802, theinput bonding pad 621 and the output bonding pad 622 of the firstsemiconductor chip 620. Further, the first bond finger 531 may beconnected to the third metal wire 803, the dummy pad 613 of the firstsemiconductor chip 610, and the fourth metal wire 804.

Subsequently, as illustrated in FIG. 6B, the input bonding pad 611′ ofthe lower first semiconductor chip 610′ of the first semiconductor chipgroup 600′ disposed at a middle level of the three first semiconductorchip groups 600, 600′ and 600″ may be electrically connected to thesecond bond finger 532 of the substrate 510 through a firstinterconnection. The first interconnection may be, for example, a firstmetal wire 811. The second bond finger 532 may correspond to a bondfinger which is connected to the dummy pad 613 of the lowermost firstsemiconductor chip 610 of the first semiconductor chip group 600. Theoutput bonding pad 612′ of the lower first semiconductor chip 610′ maybe electrically connected to the input bonding pad 621′ of the upperfirst semiconductor chip 620′. The upper first semiconductor chip 620′may be disposed on the lower first semiconductor chip 610′ through asecond interconnection, for example, a second metal wire 812. If thefirst semiconductor chip group 600′ includes three or more firstsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 612′ of the lower firstsemiconductor chip 610′ to the input bonding pad 621′ of the upper firstsemiconductor chip 620′ through the second metal wire 812 may berepeatedly applied. The interconnection scheme may be applied to all ofthe first semiconductor chips between the lowermost first semiconductorchip and the uppermost first semiconductor chip. The output bonding pad622′ of the first semiconductor chip 620′ corresponding to an uppermostsemiconductor chip of the first semiconductor chip group 600′ may beelectrically connected to the dummy pad 613′ of the first semiconductorchip 610′. The first semiconductor chip 610′ may be under the firstsemiconductor chip 620′ through a third interconnection, for example, athird metal wire 813. If the first semiconductor chip group 600′includes three or more first semiconductor chips which are sequentiallystacked, the interconnection scheme to connect the output bonding pad622′ of the first semiconductor chip 620′ to the dummy pad 613′ of thefirst semiconductor chip 610′ through the third metal wire 813 may berepeatedly applied. The interconnection scheme may be applied to all ofthe first semiconductor chips between the lowermost first semiconductorchip and the uppermost first semiconductor chip. The dummy pad 613′ ofthe lowermost first semiconductor chip 610′ may be electricallyconnected to the third bond finger 533 of the substrate 510 through afourth interconnection, for example, a fourth metal wire 814.

In some embodiments, if the first semiconductor chip group 600′ includesthree or more first semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost first semiconductor chip may beelectrically connected to a dummy pad of one of the first semiconductorchips. The first semiconductor chips may be under the uppermost firstsemiconductor chip through the third metal wire 813. The dummy pad maybe electrically connected to the third bond finger 533 of the substrate510 through the fourth metal wire 814. Alternatively, if the firstsemiconductor chip group 600′ includes three or more first semiconductorchips which are sequentially stacked, the output bonding pad of theuppermost first semiconductor chip may be electrically connected to adummy pad of one of the first semiconductor chips. The firstsemiconductor chips may be under the uppermost first semiconductor chipthrough the third metal wire 813 and the dummy pad may be electricallyconnected to the third bond finger 533 of the substrate 510 via a dummypad of another first semiconductor chip.

As described above, the second bond finger 532 of the substrate 510 maybe connected to the third bond finger 533 through a second token ringloop which includes the first metal wire 811, the input bonding pad 611′and the output bonding pad 612′ of the first semiconductor chip 610′.The second token ring loop may also include the second metal wire 812,the input bonding pad 621′ and the output bonding pad 622′ of the firstsemiconductor chip 620′. The second token ring loop may also include thethird metal wire 813, the dummy pad 613′ of the first semiconductor chip610′, and the fourth metal wire 814.

Moreover, as illustrated in FIG. 6C, the input bonding pad 611″ of thelower first semiconductor chip 610″ of the first semiconductor chipgroup 600″ disposed at an uppermost level of the three firstsemiconductor chip groups 600, 600′ and 600″ may be electricallyconnected to the third bond finger 533 of the substrate 510 through afirst interconnection. The first interconnection may be, for example, afirst metal wire 821. The third bond finger 533 may correspond to a bondfinger which is connected to the dummy pad 613′ of the lowermost firstsemiconductor chip 610′ of the first semiconductor chip group 600′. Theoutput bonding pad 612″ of the lower first semiconductor chip 610″ maybe electrically connected to the input bonding pad 621″ of the upperfirst semiconductor chip 620″. The upper first semiconductor chip 620″may be disposed on the lower first semiconductor chip 610″ through asecond interconnection, for example, a second metal wire 822. If thefirst semiconductor chip group 600″ includes three or more firstsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 612″ of the lower firstsemiconductor chip 610″ to the input bonding pad 621″ of the upper firstsemiconductor chip 620″ through the second metal wire 822 may berepeatedly applied. The interconnection scheme may be applied to all ofthe first semiconductor chips between the lowermost first semiconductorchip and the uppermost first semiconductor chip. The output bonding pad622″ of the first semiconductor chip 620″ corresponding to an uppermostsemiconductor chip of the first semiconductor chip group 600″ may beelectrically connected to the dummy pad 613″ of the first semiconductorchip 610″ under the first semiconductor chip 620″ through a thirdinterconnection. The third interconnection may be, for example, a thirdmetal wire 823. If the first semiconductor chip group 600″ includesthree or more first semiconductor chips which are sequentially stacked,the interconnection scheme to connect the output bonding pad 622″ of thefirst semiconductor chip 620″ to the dummy pad 613″ of the firstsemiconductor chip 610″ through the third metal wire 823 may berepeatedly applied. The interconnection scheme may be applied to all thefirst semiconductor chips between the lowermost first semiconductor chipand the uppermost first semiconductor chip. The dummy pad 613″ of thelowermost first semiconductor chip 610″ may be electrically connected tothe fourth bond finger 534 of the substrate 510 through a fourthinterconnection, for example, a fourth metal wire 824.

In some embodiments, if the first semiconductor chip group 600″ includesthree or more first semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost first semiconductor chip may beelectrically connected to a dummy pad of one of the first semiconductorchips. The first semiconductor chips may be under the uppermost firstsemiconductor chip through the third metal wire 823. The dummy pad maybe electrically connected to the fourth bond finger 534 of the substrate510 through the fourth metal wire 824. Alternatively, if the firstsemiconductor chip group 600″ includes three or more first semiconductorchips which are sequentially stacked, the output bonding pad of theuppermost first semiconductor chip may be electrically connected to adummy pad chip through the third metal wire 823. The dummy pad may be ofone of the first semiconductor chips under the uppermost firstsemiconductor. The dummy pad may be electrically connected to the fourthbond finger 534 of the substrate 510 via a dummy pad of another firstsemiconductor chip.

As described above, the third bond finger 533 of the substrate 510 maybe connected to the fourth bond finger 534 through a third token ringloop. The third token ring loop may include the first metal wire 821,the input bonding pad 611″ and the output bonding pad 612″ of the firstsemiconductor chip 610″. The third token ring loop may include thesecond metal wire 822, the input bonding pad 621″ and the output bondingpad 622″ of the first semiconductor chip 620″. Further, the third tokenring loop may include the third metal wire 823, the dummy pad 613″ ofthe first semiconductor chip 610″, and the fourth metal wire 824.

A first token ring group may consist of the first token ring loopbetween the substrate 510 and the first semiconductor chip group 600.The first token ring group may also consist of the second token ringloop between the substrate 510 and the first semiconductor chip group600′. In addition, the first token ring group may also consist of thethird token ring loop between the substrate 510 and the firstsemiconductor chip group 600″ The first token ring group mayelectrically connect the first semiconductor chip groups 600, 600′, and600″ to each other.

The second semiconductor chips 710, 720, 710′, 720′, 710″ and 720″ ofthe second semiconductor chip groups 700, 700′ and 700″ may beelectrically connected to the first, second, third and fourth bondfingers 541, 542, 543, and 544 of the second bond finger group through atoken ring connection structure.

Specifically, as illustrated in FIG. 7A, the input bonding pad 711 ofthe lower second semiconductor chip 710 of the second semiconductor chipgroup 700 may be disposed at a lowermost level of the three secondsemiconductor chip groups 700, 700′ and 700″. The input bonding pad 711may be electrically connected to the first bond finger 541 of thesubstrate 510 through a first interconnection, for example, a firstmetal wire 901. The output bonding pad 712 of the lower secondsemiconductor chip 710 may be electrically connected to the inputbonding pad 721 of the upper second semiconductor chip 720. The uppersecond semiconductor chip 720 may be disposed on the lower secondsemiconductor chip 710 through a second interconnection. The secondinterconnection may be, for example, a second metal wire 902. If thesecond semiconductor chip group 700 includes three or more secondsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 712 of the lower secondsemiconductor chip 710 to the input bonding pad 721 of the upper secondsemiconductor chip 720 through the second metal wire 902 may berepeatedly applied. The interconnection scheme may be applied to all ofthe second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Theoutput bonding pad 722 of the second semiconductor chip 720corresponding to an uppermost semiconductor chip of the secondsemiconductor chip group 700 may be electrically connected to the dummypad 713 of the second semiconductor chip 710 under the secondsemiconductor chip 720 through a third interconnection, for example, athird metal wire 903. If the second semiconductor chip group 700includes three or more second semiconductor chips which are sequentiallystacked, the interconnection scheme to connect the output bonding pad722 of the second semiconductor chip 720 to the dummy pad 713 of thesecond semiconductor chip 710 through the third metal wire 903 may berepeatedly applied. The interconnection scheme may be applied to all thefirst semiconductor chips between the lowermost second semiconductorchip and the uppermost second semiconductor chip. The dummy pad 713 ofthe lowermost second semiconductor chip 710 may be electricallyconnected to the second bond finger 542 of the substrate 510 through afourth interconnection. The fourth interconnection may be, for example,a fourth metal wire 904.

In some embodiments, if the second semiconductor chip group 700 includesthree or more second semiconductor chips which are sequentially stacked,the output bonding pad of the uppermost second semiconductor chip may beelectrically connected to a dummy pad chip through the third metal wire903. The dummy pad may be of one of the second semiconductor chips underthe uppermost second semiconductor. The dummy pad may be electricallyconnected to the second bond finger 542 of the substrate 510 through thefourth metal wire 904. Alternatively, if the second semiconductor chipgroup 700 includes three or more second semiconductor chips which aresequentially stacked, the output bonding pad of the uppermost secondsemiconductor chip may be electrically connected to a dummy pad throughthe third metal wire 903. The dummy pad may be of one of the secondsemiconductor chips under the uppermost second semiconductor chip. Thedummy pad may be electrically connected to the second bond finger 542 ofthe substrate 510 via a dummy pad of another second semiconductor chip.

As described above, the first bond finger 541 of the substrate 510 maybe connected to the second bond finger 542 through a first token ringloop which includes the first metal wire 901. The first token ring loopmay also include the input bonding pad 711 and the output bonding pad712 of the second semiconductor chip 710, the second metal wire 902, theinput bonding pad 721. In addition, the first token ring loop mayinclude the output bonding pad 722 of the second semiconductor chip 720,the third metal wire 903, the dummy pad 713 of the second semiconductorchip 710, and the fourth metal wire 904.

Subsequently, as illustrated in FIG. 7B, the input bonding pad 711′ ofthe lower second semiconductor chip 710′ of the second semiconductorchip group 700′ may be disposed at a middle level of the three secondsemiconductor chip groups 700, 700′ and 700″. The input bonding pad 711′may be electrically connected to the second bond finger 542 of thesubstrate 510 through a first interconnection, for example, a firstmetal wire 911. The second bond finger 542 may correspond to a bondfinger which is connected to the dummy pad 713 of the lowermost secondsemiconductor chip 710 of the second semiconductor chip group 700. Theoutput bonding pad 712′ of the lower second semiconductor chip 710′ maybe electrically connected to the input bonding pad 721′ of the uppersecond semiconductor chip 720′. The second semiconductor chip 720′ maybe disposed on the lower second semiconductor chip 710′ through a secondinterconnection, for example, a second metal wire 912.

If the second semiconductor chip group 700′ includes three or moresecond semiconductor chips which are sequentially stacked, theinterconnection scheme to connect the output bonding pad 712′ of thelower second semiconductor chip 710′ to the input bonding pad 721′ ofthe upper second semiconductor chip 720′ through the second metal wire912 may be repeatedly applied. The interconnection scheme may be appliedto all of the second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Theoutput bonding pad 722′ of the second semiconductor chip 720′corresponding to an uppermost semiconductor chip of the secondsemiconductor chip group 700′ may be electrically connected to the dummypad 713′ of the second semiconductor chip 710′ under the secondsemiconductor chip 720′ through a third interconnection. The thirdinterconnection may be, for example, a third metal wire 913. If thesecond semiconductor chip group 700′ includes three or more secondsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 722′ of the secondsemiconductor chip 720′ to the dummy pad 713′ of the secondsemiconductor chip 710′ through the third metal wire 913 may berepeatedly applied. The interconnection scheme may be applied to all ofthe second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Thedummy pad 713′ of the lowermost second semiconductor chip 710′ may beelectrically connected to the third bond finger 543 of the substrate 510through a fourth interconnection, for example, a fourth metal wire 914.

In some embodiments, if the second semiconductor chip group 700′includes three or more second semiconductor chips which are sequentiallystacked, the output bonding pad of the uppermost second semiconductorchip may be electrically connected to a dummy pad through the thirdmetal wire 913. The dummy pad may be of one of the second semiconductorchips under the uppermost second semiconductor chip. The dummy pad maybe electrically connected to the third bond finger 543 of the substrate510 through the fourth metal wire 914. Alternatively, if the secondsemiconductor chip group 700′ includes three or more secondsemiconductor chips which are sequentially stacked, the output bondingpad of the uppermost second semiconductor chip may be electricallyconnected to a dummy pad through the third metal wire 913. The dummy padmay be of one of the second semiconductor chips under the uppermostsecond semiconductor chip. The dummy pad may be electrically connectedto the third bond finger 543 of the substrate 510 via a dummy pad ofanother second semiconductor chip.

As described above, the second bond finger 542 of the substrate 510 maybe connected to the third bond finger 543 through a second token ringloop. The second token ring loop may include the first metal wire 911,the input bonding pad 711′ and the output bonding pad 712′ of the secondsemiconductor chip 710′. The second token ring loop may include thesecond metal wire 912, the input bonding pad 721′ and the output bondingpad 722′ of the second semiconductor chip 720′. The second token ringloop may include the third metal wire 913, the dummy pad 713′ of thesecond semiconductor chip 710′, and the fourth metal wire 914.

Moreover, as illustrated in FIG. 7C, the input bonding pad 711″ of thelower second semiconductor chip 710″ of the second semiconductor chipgroup 700″ disposed at an uppermost level of the three secondsemiconductor chip groups 700, 700′ and 700″ may be electricallyconnected to the third bond finger 543 of the substrate 510 through afirst interconnection. The first interconnection may be, for example, afirst metal wire 921. The third bond finger 543 may correspond to a bondfinger which is connected to the dummy pad 713′ of the lowermost secondsemiconductor chip 710′ of the second semiconductor chip group 700′. Theoutput bonding pad 712″ of the lower second semiconductor chip 710″ maybe electrically connected to the input bonding pad 721″ of the uppersecond semiconductor chip 720″. The upper second semiconductor chip 720″may be disposed on the lower second semiconductor chip 710″ through asecond interconnection, for example, a second metal wire 922. If thesecond semiconductor chip group 700″ includes three or more secondsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 712″ of the lower secondsemiconductor chip 710″ to the input bonding pad 721″ of the uppersecond semiconductor chip 720″ through the second metal wire 922 may berepeatedly applied. The interconnection scheme may be applied to all ofthe second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Theoutput bonding pad 722″ of the second semiconductor chip 720″corresponding to an uppermost semiconductor chip of the secondsemiconductor chip group 700″ may be electrically connected to the dummypad 713″ of the second semiconductor chip 710″. The second semiconductorchip 710″ may be disposed under the second semiconductor chip 720″through a third interconnection, for example, a third metal wire 923. Ifthe second semiconductor chip group 700″ includes three or more secondsemiconductor chips which are sequentially stacked, the interconnectionscheme to connect the output bonding pad 722″ of the secondsemiconductor chip 720″ to the dummy pad 713″ of the secondsemiconductor chip 710″ through the third metal wire 923 may berepeatedly applied. The interconnection scheme may be applied to all ofthe second semiconductor chips between the lowermost secondsemiconductor chip and the uppermost second semiconductor chip. Thedummy pad 713″ of the lowermost second semiconductor chip 710″ may beelectrically connected to the fourth bond finger 544 of the substrate510 through a fourth interconnection. The fourth interconnection may be,for example, a fourth metal wire 924.

In some embodiments, if the second semiconductor chip group 700″includes three or more second semiconductor chips which are sequentiallystacked, the output bonding pad of the uppermost second semiconductorchip may be electrically connected to a dummy pad through the thirdmetal wire 923. The dummy pad may be of one of the second semiconductorchips under the uppermost second semiconductor chip. The dummy pad maybe electrically connected to the fourth bond finger 544 of the substrate510 through the fourth metal wire 924. Alternatively, if the secondsemiconductor chip group 700″ includes three or more secondsemiconductor chips which are sequentially stacked, the output bondingpad of the uppermost second semiconductor chip may be electricallyconnected to a dummy pad through the third metal wire 923. The dummy padmay be of one of the second semiconductor chips under the uppermostsecond semiconductor chip. The dummy pad may be electrically connectedto the fourth bond finger 544 of the substrate 510 via a dummy pad ofanother second semiconductor chip.

As described above, the third bond finger 543 of the substrate 510 maybe connected to the fourth bond finger 544 through a third token ringloop which includes the first metal wire 921, the input bonding pad 711″and the output bonding pad 712″ of the second semiconductor chip 710″.The third token ring loop may include the second metal wire 922, theinput bonding pad 721″ and the output bonding pad 722″ of the secondsemiconductor chip 720″. The third token ring loop may include the thirdmetal wire 923, the dummy pad 713″ of the second semiconductor chip710″, and the fourth metal wire 924.

A second token ring group may consist of the first token ring loopbetween the substrate 510 and the second semiconductor chip group 700.The second token ring group may also consist of the second token ringloop between the substrate 510 and the second semiconductor chip group700′. In addition, the second token ring group may consist of the thirdtoken ring loop between the substrate 510 and the second semiconductorchip group 700″. The second token ring group may electrically connectthe second semiconductor chip groups 700, 700′ and 700″ to each other.

According to the embodiments set forth above, a plurality ofsemiconductor chips stacked on a substrate may be serially connected byat least one token ring loop. Thus, the at least one token ring loop mayreduce an amount of the current flowing through the plurality ofsemiconductor chips. In particular, the embodiments may also be equallyapplicable to stack packages having various step structures.

The embodiments of the inventive concept have been disclosed above forillustrative purposes. Those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the inventive concept asdisclosed in the accompanying claims.

What is claimed is:
 1. A stack package comprising: a substrate having a first bond finger and a second bond finger; a plurality of semiconductor chips stacked on the substrate, each of the plurality of semiconductor chips having an input bonding pad and an output bonding pad; a first interconnection electrically connecting the first bond finger to the input bonding pad of a lowermost semiconductor chip of the plurality of semiconductor chips; a second interconnection electrically connecting the output bonding pad of a lower semiconductor chip of the plurality of semiconductor chips to the input bonding pad of an upper semiconductor chip stacked on the lower semiconductor chip; and a third interconnection electrically connecting the output bonding pad of an uppermost semiconductor chip of the plurality of semiconductor chips to the second bond finger.
 2. The stack package of claim 1, wherein the plurality of semiconductor chips are stacked to have a step structure to expose the input bonding pads and the output bonding pads.
 3. The stack package of claim 1, wherein each of the first to third interconnections includes a metal wire.
 4. The stack package of claim 1, wherein the first and second bond fingers act as an input terminal and an output terminal, respectively.
 5. The stack package of claim 1, wherein the input bonding pad and the output bonding pad of each of the semiconductor chips are connected to each other through an internal circuit integrated in the corresponding semiconductor chip.
 6. A stack package comprising: a substrate having a first bond finger and a second bond finger; a plurality of semiconductor chips stacked on the substrate, each of the plurality of semiconductor chips having an input bonding pad, an output bonding pad and a dummy pad; a first interconnection electrically connecting the first bond finger to the input bonding pad of a lowermost semiconductor chip of the plurality of semiconductor chips; a second interconnection electrically connecting the output bonding pad of a lower semiconductor chip of the plurality of semiconductor chips to the input bonding pad of an upper semiconductor chip stacked on the lower semiconductor chip; a third interconnection electrically connecting the output bonding pad of an upper semiconductor chip of the plurality of semiconductor chips to the dummy pad of a lower semiconductor chip under the upper semiconductor chip; and a fourth interconnection electrically connecting the dummy pad of a lowermost semiconductor chip of the plurality of semiconductor chips to the second bond finger.
 7. The stack package of claim 6, wherein the plurality of semiconductor chips are stacked to have a step structure to expose the input bonding pads, the output bonding pads, and the dummy pads.
 8. The stack package of claim 6, wherein the first and second bond fingers act as an input terminal and an output terminal, respectively.
 9. The stack package of claim 6, wherein the input bonding pad and the output bonding pad of each of the semiconductor chips are connected to each other through an internal circuit integrated in the corresponding semiconductor chip. 